The report, Working For The Few, which will be debated at the Scotttish Parliament tomorrow, claims growing inequality has been driven by a "power grab" by wealthy elites, who have co-opted the political process to rig the economic system in their favour.
Oxfam called on attendees at this week's World Economic Forum, which brings together politicians and business leaders in the Swiss ski resort of Davos, to take a personal pledge to tackle the problem by refraining from dodging taxes or using their wealth to seek political favours.
Polling for the report found people in countries around the world - including two-thirds of those questioned in Britain - believe the rich have too much influence over the direction their country is heading.
MSPs will discuss Oxfam's latest fundraising and awareness campaign, Lift Lives for Good, which aims to tackle inequality and climate change.
Jamie Livingstone, Acting Head of Oxfam Scotland, said: "Inequality has shot up the global agenda, and it is heartening to see it being debated at the Scottish Parliament. In Scotland, as elsewhere, we cannot hope to win the fight against poverty without tackling inequality and we must do more to ensure wealth is shared more fairly."
Oxfam chief executive Winnie Byanyima added: "It is staggering that in the 21st century, half of the world's population - that's three and a half billion people - own no more than a tiny elite whose numbers could all fit comfortably on a double-decker bus.
"Widening inequality is creating a vicious circle where wealth and power are increasingly concentrated in the hands of a few, leaving the rest of us to fight over crumbs from the top table.
"In developed and developing countries alike, we are increasingly living in a world where the lowest tax rates, the best health and education and the opportunity to influence are being given not just to the rich but also to their children.
"Without a concerted effort to tackle inequality, the cascade of privilege and of disadvantage will continue down the generations.We will soon live in a world where equality of opportunity is just a dream.
"In too many countries economic growth already amounts to little more than a 'winner takes all' windfall for the richest."